MASTITIS IN DAIRY COWS by Stacy Joseph

Research TopicThis study takes a look at a common infection in dairy cattle called mastitis and tries to find a connection between individual cow hygiene and mastitis infection.

AimThe objective of this study was to determine if there is a relationship between hygiene scores of lactating dairy cattle and measures of subclinical mastitis.

Rationale My reason for choosing this topic was that I

wanted to do a research project that reflected my interest in animal science.

Also this area of research needs to be explored in more detail in Trinidad and the wider Caribbean region as there is not enough data on this topic.

Background Mastitis is defined as

an inflammation of the mammary gland.

It is the most common infection in the dairy sector that results in changes in milk composition.

Constituent Normal milk (%) Mastitic milk (%)Solid non fat 8.98 8.8Fat 35.0 3.20Lactose 4.90 4.40Total protein 3.61 3.56Total casein 2.8 2.30Whey protein 0.8 1.30Serum albumin 0.02 0.07Lactoferrin 0.02 0.10Immunoglobulin 0.10 0.60Sodium 0.06 0.105Chloride 0.09 0.147Potassium 0.17 0.157Calcium 0.12 0.04Example of compositional changes found in various studies.

Mastitis is the main reason for economic losses within the dairy cattle industry.

Milk becomes unfit for human consumption.

Production losses High veterinary

treatment costs.

Causes of Mastitis Mastitis is primarily

caused by bacteria. It is classified into

two major groups: Contagious Mastitis and Environmental Mastitis.

Contagious Pathogens

Streptococcus agalactiae

Staphylococcus aureus

Streptococcus dysgalactiae

Environmental Pathogens Coliforms

Escherichia coli Environmental

streptococci S. uberis S. bovis S. disgalactiae Enterococcus faecium Enterococcus faecalis

Progression of the Infection The udder is comprised

of four distinct secretory glands called “quarters.”

Each quarter consists of milk producing secretory tissue, known as alveoli.

Progression of the Infection The bacterium enters

the glandular tissues and affects the alveolar cells.

The bacterium produces toxins which damage and even kill the milk-secreting epithelial cells.

Mastitis can be manifested in three different ways: Subclinical Clinical Chronic

Subclinical form important because… It is 15 to 40 times more prevalent than

the clinical form. It usually precedes the clinical form. It is of longer duration and difficult to

detect. It adversely affects the quality of milk.

87%

4%

3%5% 1%

Percentage of substances in

normal cow’s milkWater Fat ProteinLactose Minerals

Since subclinical mastitis cannot be visualized, the only way to detect it is by measuring the cellular content of the milk.

Normal milk also contains white blood cells.

Whenever there is an infection such as the invasion of bacteria the white blood cells located around the infected area increase dramatically in numbers (millions/ml).

The CMT is a simple test that is commonly used to detect subclinical mastitis.The CMT can correctly predict the somatic cell count of milk from composite milk samples.

California Mastitis Test (CMT)

CMT KitA CMT Kit includes a four chambered paddle, a concentrated reagent, an empty pump bottle and complete directions and color charts.

About ½ teaspoon of milk is dispensed from each quarter into each of the four chambers of the paddle.

Conducting the CMT

An equal ratio of reagent is poured into the milk and the paddle is rotated in a circular motion to thoroughly mix contents.

Conducting the CMT

The reagent reacts with the white blood cells and the mixture thickens or gels in proportion to the amount of infection present.

Conducting the CMT

CMT Scoring ChartLeukocyte count per millilitre

Test appearance CMT score

Below 200,000 Mixture liquid, no precipitate negative

150,000 to 500,000

Slight precipitate, tends to disappear with paddle movement

Trace

400,000 to 1,500,000

Distinct precipitate but does not gel with paddle movement

1

800,000 to 5,000,000

Distinct gel formation 2

Over 5,000,000 Strong gel formation that tends to adhere to paddle. Forms distinct central peak

3

Results of the CMTAge

(years)CMT Scores

1st quadrant

2nd quadrant

3rd quadrant

4th quadrant

5 0 0 0 -4 0 - 0 0

3 ½ 0 0 0 03 0 0 0 05 - 0 0 05 0 0 0 05 0 0 0 06 0 0 0 04 0 0 0 05 0 0 0 0

Results of the CMTAge

(years)CMT Scores

1st quadrant

2nd quadrant

3rd quadrant

4th quadrant

6 0 0 0 -5 0 0 0 05 0 0 0 T

3 ½ 0 0 0 03 ½ T 0 0 -

5 0 0 0 05 0 0 0 06 - 0 0 06 0 0 0 0

2 ½ 0 0 0 0

Hygiene and Mastitis

Hygiene Scoring The environment the cow

lives in greatly influences the numbers and types of bacteria that they are exposed to.

Hygiene scoring is an effective way of providing visible evidence of the amount of exposure a cow has to a particular environment.

Transfer Mechanisms

Environmental streptococci such as S. uberis and S. dysgalactiae are mainly found in manure.

Manure can transfer to the udder in four different ways: direct transfer leg transfer Splashing tail transfer

Hygiene Score Hygiene scoring systems have

been developed to assess the cleanliness of the cows.

Three zones - lower leg, udder and upper leg and flank area.

Score each zone separately using numbered system with 1 (very clean) and 4 (very dirty).

Hygiene Scoring Card

Devised by N.B.Cook University of Wisconsin-Madison

Hygiene Scoring Card

Devised by N.B.Cook University of Wisconsin-Madison

Hygiene Scoring Card

Devised by N.B.Cook University of Wisconsin-Madison

Results of Hygiene Score

v. clean "1"

clean "2"

dirty "3"

v. dirty "4"

020406080

100120140160180200

Upper leg and Flank

Lower leg

Udder

Hygiene Scores

Perc

enta

ge o

f cow

s

Analysis of Results The relationship between hygiene scores

and measures of subclinical mastitis was strong.

All of the animals were characterized as clean and were free of subclinical mastitis.

Due to the small sample size the data could not be analyzed with a statistical program.

Conclusion Therefore, this study was unable to

precisely confirm the relationship between measures of subclinical mastitis and udder and leg hygiene scores.

Recommendations A larger study that incorporates several

study farms over a period of at least six months is needed.

Further laboratory analysis of milk samples is also needed to identify if the bacteria were predominantly contagious or environmental pathogens.

Any questions?

Thank You.

Note the deep slush that the cows have to pass though.

Entrance to the milking area.

Note the stuff on the ground is not mud but manure that has been dried by the sun.

Cows entering the milking area.

Note the mud/manure on the legs from passing through the slush at the entrance.

Milking machine in use on a cow.

Steel containers for holding milk.

Cows standing in the milking shed.

Another view of milking machine.

Area in which cow’s spend most of their time

Another view of the field.